Hammond and 7591 tubes
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FalconEddy
Audio Mastering Engineer
Well, if you use educated speculation (which I'm doing right now 
) those Hammond amps were most likely DESIGNED during the same era as the 7591's.
So, you can eliminate the really old designs. . . AV, BV, CV, BV, M, M1, M2. You can also rule out the H-40, HR-40, P-40, PR-40, and Q-40, QR-40 tone cabinets. 6V6's or 6BQ5's in those.
So, that means no B3, C3, or A-100 because they all used the same internals in different cabinets; and the amp was an earlier design (H-AO-28) which used 6V6's. Some later model A series used the H-AO-39 which used 6BQ5's. The Porta B also used 6BQ5's in their H-AO-47 amp.
The M3, M101, and M102 used an H-AO-29 amp which also used 6V6's
Early versions of the M100 aslo used an H-AO-35 reverb amp that used 6BQ5's, and the H-AO-44 reverb amp in the later models. But, still no 7591's.
The H-100 series used an H-AO-70 as the main amp which also used 6BQ5's. . . as did the L series in their H-AO-43 amp.
However, the E series designed in 1964 and produced in June of 1965 used 2-7591's in their H-AO-63 amp.
The K series also used 2-7591's in their H-AO-65 amp.
I don't have data for the H-AO-68 amp (or which Hammond model used it), but I'm fairly sure that one also used 2-7591's.
Hope this reply helped.
. . Falcon
) those Hammond amps were most likely DESIGNED during the same era as the 7591's.So, you can eliminate the really old designs. . . AV, BV, CV, BV, M, M1, M2. You can also rule out the H-40, HR-40, P-40, PR-40, and Q-40, QR-40 tone cabinets. 6V6's or 6BQ5's in those.
So, that means no B3, C3, or A-100 because they all used the same internals in different cabinets; and the amp was an earlier design (H-AO-28) which used 6V6's. Some later model A series used the H-AO-39 which used 6BQ5's. The Porta B also used 6BQ5's in their H-AO-47 amp.
The M3, M101, and M102 used an H-AO-29 amp which also used 6V6's
Early versions of the M100 aslo used an H-AO-35 reverb amp that used 6BQ5's, and the H-AO-44 reverb amp in the later models. But, still no 7591's.
The H-100 series used an H-AO-70 as the main amp which also used 6BQ5's. . . as did the L series in their H-AO-43 amp.
However, the E series designed in 1964 and produced in June of 1965 used 2-7591's in their H-AO-63 amp.
The K series also used 2-7591's in their H-AO-65 amp.
I don't have data for the H-AO-68 amp (or which Hammond model used it), but I'm fairly sure that one also used 2-7591's.
Hope this reply helped.
. . Falcon
FalconEddy
Audio Mastering Engineer
I thought I had covered that question very thoroughly about two years ago (back in July of 2008); look above your reply for all the details :scratch2:
. . Falcon
B3Nut
tubes and spinny things!
The H-100, H-200, and H-300 series use a pair of 7591's in the bass channel, and two pairs of EL84/6BQ5's in the two treble stereo channels (the H-1xx/2xx/3xx has stereo vibrato and stereo slow-scan celeste effects.)
I have an H-133 and H-182 on my project pile, the H-182's main amp took out the 7591's quite spectacularly. The plates are bubbled and delaminated! Probably lost the -24V bias voltage somehow, haven't dug into it yet.
Also, correcting an above post, the B-3/C-3/A-100 preamp (AO-28) does not use 6V6's or any other power tube. The AO-29 used in M-3 and M-100 spinets did. The A-100 had a separate main amplifier (2x6BQ5) and a reverb amplifier (AO-35 using 6BQ5's in early units, then the later AO-44 using 6GW8's in post-mid-'62 units) but the AO-28 preamp is a preamp only, with a line transformer driven by a half-section of a 12BH7.
TP
I have an H-133 and H-182 on my project pile, the H-182's main amp took out the 7591's quite spectacularly. The plates are bubbled and delaminated! Probably lost the -24V bias voltage somehow, haven't dug into it yet.
Also, correcting an above post, the B-3/C-3/A-100 preamp (AO-28) does not use 6V6's or any other power tube. The AO-29 used in M-3 and M-100 spinets did. The A-100 had a separate main amplifier (2x6BQ5) and a reverb amplifier (AO-35 using 6BQ5's in early units, then the later AO-44 using 6GW8's in post-mid-'62 units) but the AO-28 preamp is a preamp only, with a line transformer driven by a half-section of a 12BH7.
TP
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B3Nut
tubes and spinny things!
Y'all oughta get a kick out of this. 
http://www.facebook.com/photo.php?pid=30673512&l=3a6d0f9319&id=1001563581
Looks like it was in a runaway condition for a good while...
http://www.facebook.com/photo.php?pid=30673512&l=3a6d0f9319&id=1001563581
Looks like it was in a runaway condition for a good while...
AO-68 uses them.
crispycircuit
Super Member
I've wired a pair of AO 68s for stereo. Used the original input/ driver circuit (12au7) and changed out the 7591s for 6L6s(since I had some) Added a volume control and used a 300 ohm 10watt common cathode resistor. Actually sound decent, also use a preamp for more drive. I believe these could sound improved with a better front end. Anyway, I was fun for a cheap set of 20watt tube amps.
I am giving away a really nice pair 7591 to a friend on the Klipsch Forum. They are Westinghouse 1965 date code. I see pairs for around $100.00 on eBay. But I attend the Klipsch Gathering yearly. Good people. And I will build a guitar amp with the 68 iron. So won't need the 7591 pair. Also sending him a matched pair GE 5 Star triple mica 5751. I have probably 20 pair. They are 1960 date codes, perfect lettering. I told him I'd take $40.00 for the matches pair. All of these tubes were made so well, they all match on my Sencore Continental 150, gm and mu.
